Cable cutter



Oct. 29, 1963 H. RUSKIN CABLE CUTTER Filed Jan. 12, 1962 3 Sheets-Sheet 1 INVENTOR.

H E NR) RUS K IN A T TORNEY Oct. 29, 1963 H, us 3,108,373

CABLE CUTTER 4 Filed Jan. 12, 1962 s Sheets-Sheet 2 INVENTOR. HENRY RUSK/N A 7' TORNE) H. RUSKIN CABLE CUTTER Oct. 29, 1963 5 Sheets-Sheet 3 Filed Jan. 12, 1962 mnh IR A m/ H United States Patent 3,108,373 CABLE CUTTER Henry Ruskin, Bayside, N.Y., assignor to Ruskin Development & Manufacturing Corporation, Flushing, N.Y. Filed Jan. 12, 1%2, Ser. No. 165,871 16 Claims. (Cl. 30-905) The present invention relates to cable cutters, for cutting the helical metal shield that protects soacalled BX electrical cable.

BX cable is a common form of electrical cable having a number of insulated wires contained within a flexible metal shield or armor. The cable is cut to a desired length in any desired manner; and then it is necessary to remove a length of shield so as to expose a free length of the wires. At best, making the cut in the shield is considered diificult, and it may be made more so by an awkward or relatively inaccessible location of the cable. An electrician must often cut the shield after the cable has already been installed, leaving only a limited free length of the cable to work on.

An object of this invention resides in the provision of a novel form of hand tool that can be conveniently gripped with one hand and operated with the other hand in making a cut through the helically wound strip of metal that constitutes the shield of BX cable.

Another object of the invention is to provide a new form of tool for making a slant or diagonal cut across a metal convolution that forms the flexible shield around BX electrical cable, at about 45 degrees to the length of the cable. This is the preferred form of out, in contrast In the illustrative embodiments of the invention described in detail below, a saw having a circle of cutting teeth is used where the teeth extend transverse to the plane of the circle. In its preferred form, the cutter is a saw having a conical wall. The tool includes a handle portion that receives and supports the free end of the cable, and presents a portion of the cable to the cutter where the out should be made. For achieving the to a cut that is parallel to the length of the cable, for

example.

Another object of the invention resides in the provision of a novel hand tool having a rotary saw and having parts to hold a length of cable relative to the saw so that the cut will be transverse to and centered in rel-ation to any one helical convolution of metal that forms the shield of the cable.

Heretofore various tools have been proposed for cutting the shield of BX cable, using a disc form of saw. As a practical matter, the radius of a disc saw in a hand tool is small and, consequently, the curvature of the edge of the saw causes the saw to penetrate into the BX cable. As a result, Where the cut is of substantial length, the curved edge of the disc type of saw blade extends dangerously into the space inside the shield occupied by the conductors. Further, such disc-saws for cutting the shield of BX cable are ordinarily disposed so that the out is along the cable, producing an objectionably pointed projection when the helically wound shield has been out.

Electricians often use a common straight-bladed hack saw for cutting BX cable shield, holding the cable against a support. Special holding devices for the cable have also been proposed for use with a hack saw. However, the hack saw involves a back-and-forth stroke that inevitably calls for some means of support for the BX cable or a cable holder to keep the cable from hopping at each stroke of the saw. A satisfactory, eifective support is usually unavailable.

Accordingly, another object of the invention resides in the provision of a novel hand tool for cutting the metal shield :of BX cable, that can be operated conveniently while held in the two hands of the user, without depending upon a stable rest or support.

A further object of the invention resides in novel features of construction of a hand saw for cutting the shield of BX cable to avoid clumsy or awkward positions of the hands of the user; to promote stability of the tool and the cable during operation of the cutter; and in other detailed but important ways to facilitate the cutting operation.

proper angle of cut, the cable crosses the saw-tooth circle at two places. The tool presses one part of the cable against one segment of the saw, while arching or slanting the rest of the cable out of contact with the saw.

In both embodiments of the invention detailed below, the tool includes two hand-grip members pivoted together. These members have hand-grip portions forming a hollow guide space for receiving the free end of the cable to be cut. The distance between the extremity of one hollow hand-grip portion and the cutting zone provides an automatic gage for the length of metal shield that is to be removed. One of the hand-grip members provides a bearing support for the circular cutter, while the other hand-grip element presses the cable against the saw. By virtue of this arrangement, it is possible at all times to adjust the presure of the metal shield of the cable against the saw teeth. It Will be appreciated that a certain minimum of pressure is necessary for reasonably fast cutting, while excessive pressure would lock the saw against rotation.

The cable is disposed with its end contained between the two hand-grip members in both embodiments below. One of the hand-grip members in each of the specific embodiments has a channel portion that contains the end of the cable, while the rest of the cable extends across the saw and away from the tool. The saw is operated by a handcrank that is moved in circle to rotate the saw. The plane of this circle makes a small angle with an imaginary line centered along and between the hand-grip portions of the tool, apex of the angle being directed away from the person of the user. This relationship greatly facilitates use of the tool, since the users hands naturally assume comfortable positions in holding the hand-grip portions and, at the same time, in operating the hand-crank.

A related feature found in one of the embodiments contributes further to the facility of operation of the tool. The hand-crank is pivoted in a portion of the tool [that extends from one hand-grip portion, the extending portion being off-set laterally relative to the hand-grip portions. This arrangement has been found efiective in reducing a limited tendency of the tool to twist back and forth in one hand while the hand-crank is being operated.

The nature of the invention as indicated above, and further objects and features of novelty, will be more fully appreciated from the following detailed description of two embodiments which are shown in the accompanying drawings forming part of the disclosure of these embodiments.

In the drawings:

FIG. 1 is an elevation of one form of so-called cable cutter, a length of BX cable being shown in phantom in cutting position;

FIG. 2 is a fragmentary cross-sectional view of a portion of the tool in FIG. 1, as viewed from the line 2-2 of FIG. 1;

FIG. 3 is a longitudinal cross-section of the portion of the tool shown in FIG. 2;

FIG. 4 is a view of a sample piece of BX cable, illustratin-g a cut in its metal shield performed with the tool of FIG. :1;

FIG. 5 is a lateral view of another embodiment of the invention having several features in common with 3 that shown in FIGS. 1-3, and certain additional features;

FIG. 6 is another lateral view of the tool in FIG. as seen from the right-hand side of FIG. 5; and

FIG. 7 is a perspective view of the hand-tool in FIGS. 5 and 6.

Referring now to the embodiment in FIGS. 1-3, two hand-grip members 10 and 12 are shown of sheet metal, joined together at pivot 14 and having hollow hand-grip portions. The center layer 1% of the pivotal joint in FIG. 2 extends integrally from member 10; metal layer 12a is a portion of member 12 that is bent up so as to be perpendicular to the axis of pivot 14; and bracket 16 fixed to member 12 has a bearing layer 16a in the pivotal joint. Member 12 has a pair of lateral guide portions flanking member 10 to insure alignment, only one of such guide portions 12b being shown.

A rotary cutter 18 is provided, best shown in FIG. 3. This saw includes a conical-walled saw blade 20 having a circular row of cutting teeth that project transverse to the plane of the cutting-tooth circle. (This contrasts with the cutting teeth of an ordinary disc saw whose teeth project radially and thus he generally in the plane of the cutting-tooth circle.) Saw 20 is made of fiat hardened steel that is customarily used for hack-saw blades and is formed into the conical shape illustrated. The saw-blade is fixed in this shape by means of a support member 22, to which there is secured (as by welding) a cap 24 that encircles the saw-blade 20 and conforms to the outer conical surface so as to prevent the saw blade from opening up and to retain the saw against member 22. In this condition of the saw when formed into the conical shape, the ends of the blade are in direct abutment with each other, and thus resist any tendency there might be for the conical form to collapse inward due to pressure at the cutting edge. The exposed edge of saw blade 20 has a row of teeth in a circle, and these teeth project generally in line with the conical wall. The teeth have the usual set, being bent a bit to one side of the blade and the other alternately, so that they are not true geometric conical elements. Essentially, however, they extend transverse to and nearly perpendicular to the plane of the circle in which the teeth are distributed. The saw teeth have cutting edges and a rake angle chosen to effect cutting by rotation of crank 26 clockwise, as viewed from the right in FIG. 1.

Support member 22 has a raised bearing portion 22a that extends through a corresponding circular bearinghole in member 12. A hand-crank 26 having a reinforcing member 23 is fixed to saw 26' by a screw and nut 32. A tongue 28a extending from member 28 is received in a slot in member 22. Consequently, when handle 26 is rotated about the axis of bearing member 22, the handle and the saw element 2t behave as a unit. Elements 22 and 26 include circular bearing ridges 22b and 26b that provide bearing surfaces against the opposite faces of member 12.

Bracket 16 includes a guide or support portion 16b for the BX cable designated BX. Guide or hand grip member 12 includes another guide element 12c. Support 1612 and guide element 120 and 16b dispose the BX cable below-center relative to the cutting-tooth circle, as viewed in FIG. 2. A pressure element 10b causes the cable to be arched into engagement with one segment of the cutting tooth circle, at the bottom of the saw as viewed in FIG. 1. In that same figure, a portion of the BX cable is opposite to the saw-tooth circle but is arched out of the contact with the saw at the upper part of the cutting-tooth circle. Disregarding the curvature of the cable in this region, the cable extends across the saw-tooth circle along a line that slants away from the plane of the circle from the point of cutting contact.

Portion 10b of member 10 is contoured to correspond with the helical convolutions of the metal shield of the BX cable. These convolutions have characteristic ridges A and grooves B (FIG. 4) with the edge of each ridge 4 overlying and interlocking with the next adjacent convolution. Shaped portion 10b locates one convolution in centered position for cutting by the saw 20.

In using the hand tool of FIG. 1, the end of a length of BX cable is deposited in the hollow handle-grip portion of member 12 and the rest of the BX cable is then bent into the shape shown in broken lines in FIG. 1. Notably, the portions of members 10 and 12 that are to be gripped by one hand of the user extend at a definite, prominent angle to the plane in which handle 26 operates. The angle converges in the direction away from the user. The two hands of the user assume certain natural positions, conforming to this angular relationship. Consequently, it is quite easy to operate the rotary saw 18 by operating hand-crank 26.

Even though the BX cable may be loosely received between hand-grip members 10 and 12, rotation of the saw continuously in the clockwise direction (as viewed from the right of FIG. 1) causes the cable to remain in a fixed position as determined by the parts of members 10 and 12 engaged by the cable. Thus, the cable is uniformly oriented in proper relationship to the circular saw 18. A cut is made in the metal shield as illustrated in FIG. 4 that is generally considered ideal by electricans. This cut (disregarding its inconsequential curvature) is roughly at a 45-degree angle to the length of the BX cable, and forms a blunt angle to the helically wound metal band or strip that forms the shield. The cut end of such BX shield can readily be received in a junction box, electrical fixture or the like, where it is anchored in place. The nature of this cutting operation reduces to a minimum any possibility of damage to wires W in the cable when the shield is being cut.

It was noted above that the cable is disposed belowcenter relative to the cutting-tooth circle in FIG. 2 by the locating formations described, and it was noted that formations 10b conform to the helical convolution parts A and B in the cutting zone. The shield in usual BX cable is a right-hand helix, and because of this and the orientation of the cable, one convolution of the metal strip is centered for cutting. The result is shown in FIG. 4.

In practice, the saw is quite durable and can be used for making a great many cuts. However, during the life of the tool, it may be desirable to change saws. This is readily effected by removing screw 30 and replacing the unit 20, 22, 24 with a substitute saw unit. The conical form of the saw-blade adapts the saw blade to simple but effective retention by parts 22 and 24. The conical form of saw blade is of significance. The saw blade must be made of strip metal, because of practical considerations, and the circle of saw teeth has a break where the ends of the saw blade abut each other. The ends of the blade are in tight abutment, due to the tight confinement of the blade by part 24. This configuration of the saw makes it well suited to resist deformation due to cutting pressures.

Another hand tool similar to that in FIG. 1 is illustrated in FIGS. 5, 6 and 7, and has many of the desirable features of the embodiment in FIG. 1. The tool in FIGS. 57 includes two hand-grip members 40 and 42 that are formed of sheet metal and are joined at pivot 44. Saw 46 is of the same internal construction and has the same bearing detail as the saw in FIG. 3, and is fixed to handcrank 48 for operation thereby. Member 40 has an upstanding portion 40a adjacent saw 46, portion 40a having a curved notch that is contoured to fit the helical groove B of the BX cable. Similarly, member 42 has a transversely extending guide portion 42a that has a contoured edge properly shaped and angled to cooperate with the helical groove B of the BX cable. The formations 40a and 42 are located in relation to the saw to position the cable (as shown in phantom lines in FIG. 5) to the right of center of the saw. This is the same orientation of a right-hand helical-shield cable as in the embodiment of FIGS. 1-3. In this orientation, the band that forms the helical shield is centered at the cutting Zone to produce a blunt cut of the metal band as shown in FIG. 4.

Portion 46b of hand-grip member 40 is shown hooked so as to hold captive the end of the BX cable without reliance upon member 42. The hand-grip portion of member 49 is formed as a channel and contains the cable. Member 40 constitutes a gage for the length of metal shield that is to be removed for exposing a corresponding length of wire. The two hand-grip members can be manipulated by one hand of the operator for providing optimum cutting pressure between the cutter and the BX cable while the saw is rotated by operation of the handcrank with the other hand.

A compression spring 50 is provided to spread elements 40 and @2 so as to enable the user to retain a firm grip of the tool. By using a relatively strong compression spring, the user can grip the tool in one hand firmly without, however, building up excessive pressure between the cutter and the BX cable.

Hand-grip portions 40 and 42 are disposed at a convenient prominent angle to the plane defined by the sweep of handle 48, that is, perpendicular to the axis of saw 46. This angular relationship assures comfortable positions of the users hands while holding the tool and operating the saw. The importance of this feature can be best appreciated when it is realized that this tool must often be used on a length of BX cable that is partly installed and in an inconvenient position, as extending from a hole in a wall. The BX cable, when inserted in the tool, is held captive and properly oriented by both forms of tool in FIGS. 1-3 and 5-7, and can be cut in a convenient two-hand operation. In both these forms of tool, the same cutter is employed and the BX cable is arched or bowed so as to dispose a length of the cable across the circle of the cutting teeth, but the BX is engaged by the saw at only one segment of the cutter.

Members 41} and 42 include two portions, each having a channel, and the two channels constituting confronting hand-grip portions. Member 44% has an off-set portion that extends from its hand-grip channel portion. The saw is rotatably mounted in the off-set. The resulting disposition of the saw axis well to the side of an imaginary center line along the hand-grip portions has been found of distinct advantage in promoting smooth rotary operation of handcrank 48.

The foregoing represents a detailed description of two embodiments of the invention which are shown in the accompanying drawings. A number of novel features are included that contribute to the successful results. However, it will be understood that those skilled in the art will find some of these useful in other applications and in various modified forms. Consequently, the invention should be broadly construed in accordance with its full spirit and scope.

What is claimed is:

1. Apparatus for cutting the helical metal shield of BX electrical cable and the like, including a saw having a row of teeth distributed around a circle and extending transverse to the plane of the circle, means to rotate the saw, locating means for disposing a length of BX cable so as to cross the circle at two spaced-apart places, said eating means holding the cable out of contact with the saw at one of said places, and pressure means acting on the cable to bias the cable against the saw at the other of said places.

2. A hand tool for cutting the helical metal shield of BX electrical cable and the like, including a pair of handgrip members, a saw rotatably carried by one of said members, said saw having a row of teeth distributed around a circle and extending transverse to the plane of the circle, hand-crank means to rotate the saw, locating means for disposing a length of BX cable so as to cross the circle at two places and holding the cable out of contact with the saw at one of said places, pressure means 6 operable by said hand-grip members and acting on the BX cable at the other of said places to bias the cable against the saw.

3. A hand tool for cutting the metal shield of BX electrical cable and the like, including a pair of hand-grip members, a circular saw rotatably mounted on one of said members, an operating hand-crank for said saw, said saw having a circle of cutting teeth directed transverse to the plane of the circle, said hand-grip members including locating and pressure-applying portions to establish cutting contact of a segment of the saw with the cable at approximately a 45-degree angle to the longitudinal extent of the cable. 7

4. A hand tool for cutting the metal shield of BX electrical cable and the like, including a pair of handgrip members pivoted together, a circular saw rotatably mounted on one of said members, a rotatable hand-crank for operating said saw, said saw having a circle of cutting teeth directed transverse to the plane of the circle, said hand-grip members including locating and pressure-applying portions to apply cutting pressure of the saw against the cable, said hand-grip members being centered approximately about a line having a small yet substantial acute angle in relation to a plane perpendicular to the rotational axis of the hand-crank.

5. A hand tool for cutting the metal shield of BX electrical cable and the like, including a pair of hand-grip members pivoted together, said hand-grip members having confronting hand-grip portions formed to locate a length of BX cable therebetween, a circular saw rotatably mounted on one of said members and having an operating hand-crank fixed thereto, said saw having a circle of cutting teeth directed transverse to the plane of the circle, said handgrip members including locating and pressureapplying portions to apply cutting pressure of the saw against the cable, said hand-grip members being centered approximately about a line having a small yet substantial acute angle in relation to the plane of the cutting circle of the 531W.

6. Apparatus for cutting the shield of BX electrical cable and the like wherein the shield is formed of a helical metal band, including a saw having a circle of teeth directed transverse to the plane of the circle, means to rotate the saw, and means for supporting and locating a length of BX cable in cutting contact with a segment of the saw and with another portion of the cable disposed opposite but spaced from the saw at a point relatively remote from said segment of the saw, said supporting and locating means disposing the metal band of the BX cable in position for transverse contact with said segment of the saw.

7. Apparatus for cutting the helical metal shield of BX electrical cable and the like, including a saw having a circle of teeth directed transverse to the plane of the circle, means to rotate the saw, and means for supporting and locating a length of BX cable in cutting contact with one segment of the saw and with another portion of the cable disposed opposite to but spaced from another segment of the saw at a point relatively remote from said one segment of the saw, said supporting and locating means disposing the BX cable at approximately 45-degrees relative to said segment of the saw.

8. Apparatus for cutting the metal shield of BX electrical cable and the like having helical convolutions, including means for supporting a length of cable with a portion of the cable disposed in a definite position, a saw having a circle of cutting teeth directed transverse to the plane of the circle and toward said portion of the cable, means supporting said saw for rotation about the center of the circle and with the plane of the circle disposed at a small acute angle with said portion, lengthwise, of the cable and with a segment of the saw disposed opposite said portion of the cable and transverse to a convolution of.

said cable portion, means for rotating said saw, and means for maintaining cutting pressure of the BX cable against the saw.

9. A hand tool for cutting the metal shield of BX electrical cable and the like, where the shield is formed of a right-hand helical band of metal, said hand-tool including a pair of hand-grip members pivoted together and including confronting hollow hand grip portions formed to receive the BX cable therebetween, one of said members having a projecting portion extending as an offset from the hand-grip portion thereof, a rotatable saw having a circle of cutting teeth that project transverse to the plane of the circle, said saw being mounted in position to be crossed by the cable extending from said handgrip portions, a hand-crank for operating said saw, and pressure-applying means for biasing the cable into cutting contact with only one segment of the saw.

10. A hand tool for cutting the metal shield of BX electrical cable and the like, including a pair of hand-grip members pivoted together and formed to retain a length of BX cable, a circular saw rotatably mounted on one of said members and having an operating hand-crank fixed thereto, said saw having a circle of cutting teeth directed transverse to the plane of the circle, said hand-grip members including locating and pressure-applying portions to establish cutting contact of the saw with the cable, said hand-grip members having companion hand-grip portions and one of said hand-grip members having a portion offset from the hand-grip portion and a rotary bearing for said saw in said off-set portion.

11. A hand tool for cutting the metal shield of BX electrical cable and the like, the shield being in the form of a right-hand helical :band, said tool including a pair of hand grip members pivoted together, at least one of said members having a hand-grip portion formed as a channel whose open side faces a hand-grip portion of the other or companion hand-grip member, said channel being proportioned to receive and loosely confine a length of BX cable, a saw rotatably supported on one of said members and having an operating hand-crank fixed thereto, said saw having a circle of cutting teeth extending transverse to the plane of the circle, cable-supporting means disposed relative to said saw so as to locate a part of the cable opposite the saw in position to cross the circle slightly to the right of the center thereof at two portions of the saw that are, respectively, relatively near to and remote from said hand-grip portions, said supporting tmeans spacing one portion of the cable out of contact with said remote portion of the saw, and means on said companion hand-grip member to press another portion of said cable into cutting contact with said near portion of the saw, said last-named means including a formation that is complementary to the cable and arranged relative to the saw to center one helical band of the helical shield in position to be cut.

12. A hand tool for cutting the shield of BX electrical cable and the like, where the shield is formed of a righthand helical band of metal, said hand tool including a pair of hand-grip members pivoted together and including confronting hand-grip portions formed to receive the cable therebetween, one of said members having an offset portion extending from the hand-grip portion thereof, a saw rotatably mounted in said offset portion and having a circle of cutting teeth that project transverse to the plane of the circle, a hand-crank fixed to said saw and mounted for motion in a plane that forms a small but substantial angle to said hand-grip portions, said members having locating and pressure-applying parts that dispose the BX cable so as to cross the circle of cutting teeth to the right of the center thereof, with the cable extending 0 opposite two portions of the saw that are, respectively, relatively remote from and near to said hand-grip portions, said parts lifting the BX cable out of contact with the cutting teeth at said remote portion of the saw and pressing the cable into contact with the saw at said near portion of the saw, the latter portion of the saw forming an angle of approximately 45-degrees with the length of the cable at that point, and said locating parts including means complementary to the helical band of metal and effective to center such band at the segment of the saw in contact with the cable.

13. A hand tool for cutting the helical metal shield of BX electrical cable and the like, including a pair of hand grip members having means for supporting and orienting a portion of the cable, a conical saw having a relatively large-diameter base and a smaller-diameter circle of cutting teeth along a saw-toothed edge opposite the base, said hand-grip members having means supporting said saw for rotation about a conical axis, hand-crank means for rotating the saw and means operable by said handgrip members for maintaining cutting pressure of the cable against a segment of the saw.

'14. Apparatus for cutting the shield of BX electrical cable and the like wherein the shield is formed of a helical metal band, including a steel saw blade made of an initially fiat strip shaped and flexed into conical form with a large-diameter base and a smaller-diameter saw-toothed edge, means holding the ends of the strip in firm abutment with each other, means to rotate the saw blade, and means for supporting and locating a length of BX cable in cutting contact with a segment of the saw blade and with another portion of the cable disposed opposite but spaced from the saw blade, at a point relatively remote from said segment of the saw blade, said supporting and locating means disposing the metal band of the BX cable in position for transverse contact with said segment of the saw blade.

15. A conical saw including a rotatable bearing memher, a steel saw blade formed of an initially flat strip and erected into conical form with the ends of the strip in abutment, a confining member tightly engaging the outside surface of the saw blade adjacent the larger-diameter edge thereof for holding said ends of the strip in tight abutment, said confining member being secured to said rotatable member for holding the saw blade assembled to the rotatable member, and said saw blade having an exposed smaller-diameter saw-toothed edge.

16. Apparatus for cutting the metal shield of BX electrical cable having helical convolutions, including a saw having a row of teeth distributed around a circle, the teeth extending transverse to the plane of the circle, means to rotate the saw, locating means for disposing a length of BX cable at approximately a 45-degree angle to a segment of the saw and with a convolution of the BX cable transverse to and approximately centered at said segment of the saw, and means bearing against the cable to press said convolution against said segment of the saw.

References Cited in the file of this patent UNITED STATES PATENTS 2,493,941 Belden Jan. 10, 1950 2,637,903 Mallaseh May 12, 1953 2,642,651 St. Palley June 23, 1953 2,687,560 St. Palley Aug. 31, 1954 2,796,657 Schlueter June 25, 1957 2,878,550 Sehlueter Mar. 24, 1959 

1. APPARATUS FOR CUTTING THE HELICAL METAL SHIELD OF BX ELECTRICAL CABLE AND THE LIKE, INCLUDING A SAW HAVING A ROW OF TEETH DISTRIBUTED AROUND A CIRCLE AND EXTENDING TRANSVERSE TO THE PLANE OF THE CIRCLE, MEANS TO ROTATE THE SAW, LOCATING MEANS FOR DISPOSING A LENGTH OF BX CABLE SO AS TO CROSS THE CIRCLE AT TWO SPACED-APART PLACES, SAID LOCATING MEANS HOLDING THE CABLE OUT OF CONTACT WITH THE SAW AT ON OF SAID PLACES, AND PRESSURE MEANS ACTING ON 